It is the largest of the three portals and is dedicated to Jesus. It is built with inclined walls that extend from the doors to the columns between the archivolts, which are born from the capitals of the latter. The central archivolt is organized around an arch with five lobes that guides it and ends in the window of the central tympanum. The walls have grooves and six arrises that emerge from an earthen bank, interrupted by pedestals with sculpted plants and domestic birds. In these pedestals are niches that house the statues of the adorations and the Nativity crowning the mullion. The portico presents a series of scenes of the birth of Jesus: the Annunciation, the Coronation of Mary, the Adoration of the Kings and the Adoration of the shepherds, the latter works by Ros i Bofarull in 1981-1982. Also depicted are the star of Bethlehem and the signs of the Zodiac, arranged as on the night of Jesus' birth (Aries, Taurus, Gemini, Cancer, Leo and Virgo), as well as musical angels with classical (harp, bassoon and violin) and folk instruments (guitar, tambourine and bagpipes), along with the 59 rosary beads that surround the window. On the lintel of the doors is inscribed "Gloria in excelsis Deo et in terra pax hominibus bonae voluntatis". There are also several representations of plants.

The door of Jesus is separated by a mullion that presents the tree of Jesse, detailing the genealogy of Christ. At the base is the serpent biting the apple, symbol of original sin, protected by a cylindrical wrought iron grille at the bottom of the column, the work of the blacksmith Joan Oñós. Above the capital is the Nativity scene, a work by Jaume Busquets (1958), accompanied by a choir of child angels (created by Etsuro Sotoo in 2000) holding phylacteries with the inscription "Jesus est natus. Venite, adoremus", while the birds are heading to the cradle, as in the popular Catalan carol "El cant dels ocells" (The song of the birds).

The portal culminates with the Tree of Life, symbol of the triumph of life and the legacy of Jesus. Here we find the anagram of Jesus with the letters JHS (from Jesuchristus or Jesus Hominum Salvator, Jesus Savior of Humanity), in a Greek cross, with the letters alpha and omega representing the beginning and the end. Surrounding it are incense-bearing angels and bearers of bread and wine, symbols of the Eucharist. Above the anagram is a family of pelicans, a bird that also symbolizes the Eucharist, with an egg representing the origin and fullness of life and nature. Ascending, two stairs symbolize the ascension to God, and a cypress tree represents eternal life, with a group of doves symbolizing the faithful who approach God. Finally, there is a representation of the Holy Trinity, with the Greek letter tau, initial of the name of God in Greek (Theos), the X of Jesus (for the Greek letter chi, initial of Christ in Greek) and the dove of the Holy Spirit.